HELIX Report Summary

Project Context and Objectives:HELIX focuses primarily on potential climate change impacts and adaptation at global warming above 2ºC, with an additional focus on 1.5ºC. Although the Paris Agreement commits its signatories to holding global warming to well below 2 ºC and pursuing efforts to limit warming to 1.5ºC, the emissions pathways implied by the current Nationally Determined Contributions would still lead to warming well in excess of 2 ºC. Policymakers, businesses and other decision-makers therefore need to understand impacts at a range of levels of global warming, and also begin to plan ahead for adaptation to changes in climate associated with higher levels of global warming. This requires coherent information on the potential conditions which may need to be adapted to, and the consequences of different courses of adaptation action. Alongside this, ongoing international negotiations on limiting global warming also require clear information on the consequences of different levels of climate change.

While a vast array of projections, scenarios and estimates of future climate change and its impacts already exists, much of this is conflicting, unclear, of unknown levels of certainty and difficult to apply to inform decisions. The rate of future change will be a critical factor in the vulnerability or resilience of societies to the changing climate, because ongoing economic development will affect the sensitivity of societies to weather and climate, and adaptation measures will require time to be identified, planned and implemented. Interdependencies between different impacts, both biophysical and socio-economic, make the problem even more complex.

A further issue is that decisions relating to climate change often require information over a wide range of scales, from global to local. The information currently available is often inconsistent across these scales. Different methods are used for addressing different questions, and lack of consistency can lead to confusion and potentially exposes decision-makers to risks of poor decisions, either because incomplete information is available or because the available information is too varied and inconsistent to be useful.

HELIX is addressing these issues by developing a clear, coherent, internally-consistent view of a small, manageable number of “future worlds” under higher levels of global warming reached under a range of physical and socio-economic circumstances, including consideration of different adaptation scenarios, supported by advice on which aspects are more certain and which less certain. These are being delivered through ground-breaking scientific research across a range of physical, natural and social science disciplines, in close engagement with experienced users of climate change information to ensure appropriate focus, clarity and utility. Both the research and the engagement with users consider a range of scales from global to local, with internal consistency across the scales being a priority.

The objectives of HELIX are:

1. Develop coherent, internally-consistent global scenarios of the combined natural and human world at 2, 4 and 6ºC global warming, including reaching this level early (2060s) or later (after 2100) and with and without pro-active adaptation planning by society. The focus will be on land and coastal impacts and their socio-economic consequences: food, water and energy security; coastal and river flooding; infrastructure; ecosystems and biodiversity; health; migration; and risk of conflict

2. Provide additional detail for focus regions of Europe, northern sub-Saharan Africa and South Asia, with active contribution from stakeholder groups and decision-makers in the regions.

3. Provide a reliable assessment of confidence in the different components of these scenarios, based on a comprehensive assessment of uncertainties throughout the different component of the projections

4. Carry out a preliminary assessment of impacts at 1.5 ºC global warming using methods consistent with our main work on impacts of higher levels of warming.

5. To ensure the research addresses the needs of decision-makers, through both its implementation and communication.

Project Results:We have produced a number of scenarios of 21st Century climate change using two high-resolution Atmospheric General Circulation Models (GCMs), EC-Earth and HadGEM3 driven by sea surface temperature and sea ice from existing lower-resolution simulations in the 5th Coupled Model Intercomparison Project (CMIP5) multi-model ensemble. These are being used to drive models of biophysical impacts of climate change such as fresh water availability, crop yield and biodiversity loss. These in turn will be used to drive socioeconomic impacts assessments.

We are also assessing impacts at regional scales in Europe, northern hemisphere sub-Saharan Africa, using higher-resolution Regional Climate Models (RCMs) driven by some of the same CMIP5 GCMs. These studies are informed by stakeholder workshops held in the UK, Senegal, Ethiopia, India and Bangladesh during May-August 2014. Participants were from a range of backgrounds, including government departments, commercial companies, NGOs and local farmers.

We have also investigated environmental factors influencing migration in a number of countries in Africa and Asia.

It is also important not to assume that models give us a complete picture of future climate risks. With such a complex system, major changes may occur that are not captured by current model projections. We are investigating the potential impacts of passing tipping points in the climate system, such as a collapse of the Atlantic Meridional Overturning Circulation (AMOC).

Main results so far:

Recent global emissions, and those projected for the next few years on the basis of Gross Domestic Product, are tracking the Intergovernmental Panel on Climate Change (IPCC) high emissions scenario.

By the 2060s, the high emissions scenario leads to global warming exceeding 2°C in all IPCC climate models. The fastest-warming models simulate 4°C warming by this time, and at least one reaches 6°C by this time. There are, however, a number of different emissions scenarios that could lead to any particular levels of global warming being reached.

At any of these levels of global warming, local changes may be larger or smaller. Greater warming is projected over most land areas, especially continental interiors. Warming is also greater nearer the poles, but smaller over most ocean regions.

Uncertainties in regional rainfall changes are very large. In all focus regions of HELIX – Europe, West Africa, East Africa and the Indian Sub-Continent – some models project wetter conditions while others project drying. This uncertainty becomes larger at higher levels of global warming.

The uncertainties in regional climate change at a particular level of global warming feed through into uncertainties in impacts, and further uncertainties arise from the processes involved in the impacts themselves. For example, different crop models give very different changes in crop yield at regional scales, resulting in widely-varying economic impacts which in many cases can be either positive or negative depending mainly on the choice of model. Similar conclusions are drawn in relation to impacts on flooding and water availability – in many locations, some models suggest increases while others suggest decreases.

A collapse of the AMOC, while apparently unlikely, would be expected to lead to major cooling of the North Atlantic region an western Europe, and could also have substantial impacts in other regions around the globe. While some of these could be viewed as beneficial, such as increased plant productivity in north-eastern Brazil, many would probably be viewed as negative as they involved loss of vegetation productivity in agricultural areas.

Potential Impact:The final results of HELIX are expected to be a set of scenarios which demonstrate the range of possible states of the environment in key regions and across the globe in relation to food, fresh water, flooding and biodiversity at specific global warming levels (SWLs) of 1.5, 2, 4 and 6°C, and the potential (or limits) for societal adaptation to these states. The potential impacts of these results will be a contribution to improved decision-making on mitigation and long-term adaptation to climate change, through improved awareness and understanding of the risks associated with potential changes in regional climate. The research may inform ongoing development of emissions reductions policies by parties to the United Nations Framework Convention on Climate Change (UNFCCC) under the terms of the Paris Agreement. Other economic impacts, in conjunction with advice from other ongoing scientific research, could be to contribute to better spending decisions in relation to long-term adaptation to climate change by the Commission, governments of EU member states, other governments, the private sector, non-governmental organisations and civil society. This could include either or both: (i) avoidance of unnecessary expenditure on adaptation measures for threats which may actually be low risk, and/or (ii) improved confidence or urgency in expenditure on adaptation measures for threats which are high risk. HELIX should not, and will not, be the sole source of information on which such decisions will be based; nevertheless, our research will make a direct contribution to the wider knowledge base and also make indirect contributions by demonstrating improved methodologies which can be taken up by future research.

Wider societal implications, again through HELIX contributing as part of a wider knowledge base, could include improved resilience of society to long-term climate change as a result of improved adaptation or avoided maladaptation, and/or indirect benefits from reduced opportunity costs of unnecessary adaptation. Moreover, we expect that our communication of our research will lead to an improved public understanding of science relating to climate change. This could have further implications for public engagement with public policy on climate, and potentially even contribute to an influence on the popular mandate for such policies.

Specifically, the results of our research on the plausible range of changes in freshwater availability and crop yields could contribute to an understanding of the risks or opportunities that climate implies for water and food security, which could help inform policymaking for international development and long-term infrastructure planning, alongside other considerations. Similarly, our research on the range of implications for human health and the two-way relationships between climate change vulnerability and migration could also contribute to policymaking in support of the long-term development of healthcare support and settlement planning. Our research on the range of potential impacts on ecosystems and biodiversity may contribute to policy and long-term planning on conservation.

These impacts of our research are most likely to be seen in relation countries included in our Focus Regions; Europe, northern Hemisphere sub-saharan Africa (Senegal, Kenya and neighbouring countries), and south Asia (particularly India and Bangladesh). This could include national governments, regional and local authorities within these countries, wider organisations above the National level (eg: the European Commission), multi-national organisations and other large corporations, NGOs. However, since HELIX also has a global scope as well as our focus regions, the research could also lead to impact in other countries outside of our focus regions and at the global level via the United Nations.